Abstract
We demonstrate a simple method of transforming vector magnetograms to heliographic coordinates. The merits of this transformation are illustrated using a vector magnetogram obtained with the MSFC vector magnetograph 80 minutes prior to a white light flare in active region AR 4474 on 25 April, 1984. The original magnetogram shows strong magnetic shear along the neutral line at both the flare site and a non-flaring site. The transformation of the magnetogram to heliographic coordinates shows that the elimination of projection effects results in a much shorter length of the sheared region at the non-flaring site than what is inferred from the image plane vector magnetogram. The length of the sheared region at the flare site is relatively less affected by the transformation.
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References
Hagyard, M. J.: 1987, Solar Phys. 107, 239.
Hagyard, M. J. and Rabin, D. M.: 1986, Adv. Space Res. 6, 7.
Hagyard, M. J., Cumings, N. P., West, E. A., and Smith, J. E.: 1982, Solar Phys. 80, 33.
Hagyard, M. J., Smith, J. B., Jr., Teuber, D., and West, E. A.: 1984, Solar Phys. 91, 115.
Kurokawa, H., Hanaoka, Y., Shibata, K., and Uchida, Y.: 1987, Solar Phys. 108, 251.
Moore, R. L., Hagyard, M. J., and Davis, J. M.: 1988, Solar Phys. (in press).
Wilkinson, L. K., Emslie, A. G., and Gary, A.: 1988, Solar Phys. (in preparation).
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National Research Council Resident Research Associate on leave from Indian Institute of Astrophysics, Bangalore 560034, India.
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Venkatakrishnan, P., Hagyard, M.J. & Hathaway, D.H. Elimination of projection effects from vector magnetograms: The pre-flare configuration of active region AR 4474. Sol Phys 115, 125–131 (1988). https://doi.org/10.1007/BF00146234
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DOI: https://doi.org/10.1007/BF00146234